SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '115ac293fcaab8b5169ad029869acd9c84a420184ebe91a9e109df32a486e976' 
  AND token = '1O8UPrb2JUVtzatbcRqrIDi9lG1RGk1/ivahGj9ta4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}